Mobile commerce is big business to eBay. And the largest online marketplace in the world realizes that this cash cow can be milked even further. As a result, …

Mobile commerce is big business to eBay. And the largest online marketplace in the world realizes that this cash cow can be milked even further.

As a result, on Friday, eBay unveiled its newest campaign: “When it’s on your mind, it’s on eBay.”

The advertising campaign speaks to today’s “on-demand shopper,” who prefers to shop anywhere, anytime with a mobile device, eBay says, noting that the campaign aims to prime the market for what will be eBay’s largest mobile shopping season ever as the company continues to innovate and enable consumers to shop “how they want, when they want.”

“eBay’s target customers are shopping enthusiasts — people who are passionate about shopping, whenever and wherever the moment of inspiration strikes,” says Richelle Parham, chief marketing officer for eBay. “Shopping enthusiasts are heavy online users with a particular affinity for mobile shopping, and this campaign extends eBay’s powerful brand to reach them at the moment they want to shop.”

The campaign was brought to life by independent San Francisco ad agency Venables Bell & Partners.

The effort by eBay pays special attention to prospective shoppers in categories such as fashion, motors and electronics.

Shopping enthusiasts use mobile devices to shop more than any other category of shopper. Sixty percent of fashion enthusiasts and 65 percent of electronics enthusiasts own smartphones, compared to less than 30 percent of the general public. eBay research has shown that these shoppers appreciate the excitement of the eBay marketplace and like to shop on eBay at the moment inspiration strikes.

“When the company that revolutionized how people shop asks you to do something big and new, you get excited,” says Paul Venables, executive creative director at Venables Bell & Partners. “For this campaign, we tapped into the psyche of passionate shoppers and then demonstrated why eBay is the answer.”

Using the simple call to action, “But it new. Buy it now,” the campaign reinforces the shopping experience on eBay today. Sixty-two percent of the more than 200 million live listings at any given time are fixed price and 70 percent are new products. Mobile sales on eBay are expected to exceed $4 billion by the end of 2011, and eBay’s suite of mobile applications have been downloaded nearly 50 million times, with one purchase made every second through mobile, showing a strong demand for shopping on the go.